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Published November 12, 1993 | public
Journal Article

Crystal structure of neocarzinostatin, an antitumor protein-chromophore complex

Abstract

Structures of the protein-chromophore complex and the apoprotein form of neocarzinostatin were determined at 1.8 angstrom resolution. Neocarzinostatin is composed of a labile chromophore with DNA-cleaving activity and a stabilizing protein. The chromophore displays marked nonlinearity of the triple bonds and is bound noncovalently in a pocket formed by the two protein domains. The chromophore π-face interacts with the phenyl ring edges of Phe^(52) and Phe^(78). The amino sugar and carbonate groups of the chromophore are solvent exposed, whereas the epoxide, acetylene groups, and carbon C-12, the site of nucleophilic thiol addition during chromophore activation, are unexposed. The position of the amino group of the chromophore carbohydrate relative to C-12 supports the idea that the amino group plays a role in thiol activation.

Additional Information

© 1993 American Association for the Advancement of Science. 24 June 1993; accepted 13 September 1993. We thank L. Joshua-Tor and B. T. Hsu for their many contributions to this project, P. J. Bjorkman for discussions, and P. van Roey for providing the refined MCM coordinates. NCS powder was a generous gift of Kayaku Co., Ltd. Supported by NIH (CA47148) (A.G.M.), with partial support of the x-ray facility (GM45162) (D.C.R.) and instrumentation provided by the Beckman Institute and the Irvine Equipment fund.

Additional details

Created:
August 20, 2023
Modified:
October 19, 2023